LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie

Possible Past Hybridization Among Desmognathus ochrophaeus in Canadice Lake: An Ecological Survey Exploring Desmognathine Salamanders and the Competitive Exclusion Hypothesis in the Western Finger Lakes of New York State

Dusky Salamanders are a varied group of sister taxa found in Northeastern North America. Two species, Desmognathus fuscus and Desmognathus ochrophaeus, have geographically overlapping ranges. In addition, they are very morphologically similar, share many niche requirements, and are found in extremely similar or even the same salamander communities. These shared traits have been posited to arise from the influence of niche conservatism during their species’ evolutions. Also, despite their physical similarities they are historically found not to hybridize on a large scale, nor have ever had a full population merge recorded. Therefore, it appears that the community ecology of these species does not seem to follow the ecological theory of Competitive Exclusion. This study consists of both an ecological and genetic survey to determine if there are any variables that separate both populations observed in the field. The hypothesis is that there will be a low instance of hybridization in both populations, and that there will be ecological differences associated with population densities where they overlap. Also, where they do overlap, I predicted that there was an observable benefit to both species that overrides their need for competition of resources. The results of this study were that the two distinct morphological groups observed shared identical haplotypes in the mitochondrial gene tested, showing a single population. In addition, it was also concluded that there was no statistical difference in the measured ecological variables for both morphologies, thus failing my hypothesis by both measures. This study took place in the Western Finger Lakes (NY) basin, within the wetland/stream around Canadice Lake

Driver-pressure-impact and response-recovery chains in European rivers: observed and predicted effects on BQEs

The report presented in the following is part of the outcome of WISER’s river Workpackage WP5.1 and as such part of the module on aquatic ecosystem management and restoration. The ultimate goal of WP5.1 is to provide guidance on best practice restoration and management to the practitioners in River Basin Management. Therefore, a series of analyses was undertaken, each of which used a part of the WP5.1 database in order to track two major pathways of biological response: 1) the response of riverine biota to environmental pressures (degradation) and 2) the response of biota to the reduction of these impacts (restoration). This report attempts to provide empirical evidence on the environment-biota relationships for both pathways

Mapping the Epoch of Reionization with C+ Line Tomography

Our KISS program has laid the theoretical foundations for probing the epoch of reionization with C+ tomography measurements, developed unique lithographed millimeter-wave spectrometer technology, and initiated a first-light C+ experiment named TIME-Pilot. With KISS support we have carried out the following investigations: 1) Developed the case for line intensity mapping methods to study the epoch of reionization using singly ionized carbon (C+), typically the most luminous emission line in galaxies. The theoretical studies not only explored the amplitude of the signal, and the usefulness in determining physical properties of the partially ionized intergalactic medium, but also the effects of foreground confusion from low-redshift galaxies. Our team made the first calculations of C+ clustering fluctuations from the reionization epoch, and estimated the effect of foreground galaxy confusion, largely from CO line emission at z ~ 1. We also authored the first papers on tomographic measurements with the Ly emission line, which shows great promise for near-infrared intensity mapping measurements with the SPHEREx SMEX mission concept. 2) Developed a complete design for a first-detection instrument of [CII] large-scale clustering emission named TIME-Pilot, based on an array of 32 novel waveguide spectrometers. The spectrometers are mounted in a linear array in two polarizations, and observations are carried out by scanning the detectors in a 1-deg linear strip, which maximizes depth (small survey area) while preserving sensitivity on large scales (long scan length). 3) Demonstrated the key waveguide spectrometer technology, which confines radiation in 2 dimensions and the power propagates between parallel plates and is dispersed and collimated by a curved grating. The waveguide spectrometers greatly reduce the mass and volume that would otherwise be required with a conventional 3-d grating spectrometer. 4) Demonstrated a prototype superconducting detector array. These high-sensitivity superconducting bolometers are mounted on the focal surface across multiple spectrometers, and read out by superconducting current amplifiers. The devices present unique micro-machining challenges to produce edge-butted sub-arrays that do not leave spectral gaps between channels. 5) Completed the full cryogenic system for the instrument. We commandeered an existing 4 K cryostat from another project, and added cooling stages to an ultimate temperature of 220 mK to meet the TIME-Pilot cooling requirements. The system is fully tested and operational. 6) Formed a partnership with ASIAA in Taiwan, led by Tzu-Ching Chang who attended the original KISS study. ASIAA is providing major hardware components for the TIME-Pilot instrument, and in the past year have developed a prototype of the spectrometer, and procured cables and cryogenic coolers. ASIAA has also become the managing institution for the James Clerk Maxwell Telescope (JCMT) in Hawaii, and ideal facility for carrying out observations with the instrument